A variable focus lens is a lens of which a refraction index is variable. In a conventional liquid lens as a representative variable focus lens, a focal length has been controlled by roughly two methods. According to a first method, in a state where a liquid material is filled under a polymer film, an electro-mechanical actuator is operated to adjust a volume of the liquid material, so that a shape and/or a height of the polymer film are modified. According to a second method, by electrically controlling a conductive liquid, and phases of two liquids which are nonconductors and are not mixed with each other, a focal length is controlled. In particular, the former method requires a complicated structure such as the liquid, the polymer film, and the electro-mechanical actuator for controlling a volume, and also needs a motor and a fixed support to be additionally synthesized around a lens. Therefore, it is difficult to synthesis a variable focus lens in a small size, and, thus, it is difficult to control micro-scale curves. Further, since the conventional method has used a thin metal thin film as an electrode, it has been limited in synthesis a flexible or transparent electrode.